Method for encapsulating a topical composition

ABSTRACT

A method of encapsulating a topical composition in a breakable capsule, includes the steps of elastically deforming at least a portion of a first deformable film that is impermeable to the composition so as to constitute at least one blister; injecting the topical composition into the blister; applying a second film that is impermeable to the composition onto the first film so as to close the blister; and sealing the second film and the first film together around the periphery of the blister, the portion of the first film being suitable for shrinking after release of the capsule so as to cause the pressure inside the capsule to be greater than atmospheric pressure. While the capsule is being made, at least one weak region is made in the blister, thus making the capsule suitable for being broken by exerting pressure on the capsule.

BACKGROUND OF THE INVENTION

The present invention relates to a method of encapsulating a topicalcomposition in a breakable capsule.

The intended field of application is particularly but not exclusivelythat of pads containing cream type cosmetic compositions.

Powder puffs have been used for a long time in cosmetics to deposit andspread face powder over the face. They are generally received in the lidof the box containing the powder, and powder is taken from the box bypressing the puff against the supply of powder.

The need has also been felt to spread liquid or semiliquid substances onthe face, in particular creams for taking care of the skin, andrequiring pads of a different kind, and in particular pads that aredisposable. That makes it necessary to have available, independently,both the cream for spreading in a receptacle and the disposable pad forputting the cream onto the skin and for spreading it, and in somecircumstances that does not present any difficulty.

In other circumstances, that are more occasional, particularly whentesting samples, or when making an application in an unusual place, apad has been devised in which the substance for spreading is adjacent tothe applicator in a small container that is easy to open and thatcontains sufficient substance for one application.

Such single-use pads are difficult to manufacture automatically, and inparticular it is difficult to make the capsule that forms the smallcontainer.

BRIEF SUMMARY OF THE INVENTION

An object of the present invention is to provide a method of producingcapsules containing the composition for spreading, which capsules areeasy to open.

Another object of the present invention is to propose applying thecapsule production method to making single-use pads containing thecomposition for spreading.

These objects are achieved by a method of encapsulating a topicalcomposition in a breakable capsule constituted by at least a firstdeformable film that is impermeable to said composition, the methodcomprising the following steps: a first step in which at least a portionof said first film is deformed elastically so as to constitute at leastone blister; a second step in which said topical composition is injectedinto said blister; a third step in which a second film that isimpermeable to said composition is applied onto said first film so as toclose said blister; and a fourth step in which said second film and saidfirst film are sealed together around the periphery of said blister,said portion of said first film being suitable for shrinking afterrelease of said capsule so as to cause the pressure inside the capsuleto be greater than atmospheric pressure; and while said capsule is beingmade, at least one weak region is made at least in said blister, thusmaking the capsule suitable for being broken by exerting pressure onsaid capsule.

The sequence of steps in making the capsule enable an automatic methodto be applied to producing a capsule whose mechanical properties arewell adapted to the problem of opening said capsule, with opening beingperformed merely by applying pressure between two fingers, whileproduction costs are kept down to an acceptable level.

It will be understood that the method consists in a first step in makinga cavity in an elastically deformable film which would normally beplane, with the topical composition for spreading on the skin then beingintroduced into the cavity.

The cavity is held in shape during the steps of filling, applying thesecond film, and sealing. Thus, when the capsule is released, the firstfilm retains substantially the shape it has been given since thehermetically closed capsule contains said composition. However, giventhe elasticity of the film, on being released, i.e. when the capsule isreleased, it applies pressure on said composition. Thus, the pressurewhich acts on the composition is equal to atmospheric pressure plus thepressure induced by the elasticity of the film.

The system for opening the capsule is provided by local weakening of thefilm that constitutes the blister. Thus, pressure exerted on the capsuleincreases internal pressure, causing said capsule to be pierced in itsweak region, thereby releasing the topical composition. It will beunderstood that the pressure to be exerted on said capsule becomes allthe more effective in releasing the composition contained therein withincreasing pressure inside the capsule as induced by the film.

According to another feature of the method, said portion of the firstfilm constituting said blister is subjected to deformation that is bothplastic and elastic such that said first film shrinks in part after saidcapsule has been released, whereby the pressure inside the capsule isnot less than atmospheric pressure.

It is not easy to obtain deformation that is purely elastic leading tooptimum pressure inside the capsule, and as a general rule thedeformation obtained is accompanied by structural modification to thefilm giving rise to a fraction of deformation that is irreversible, i.e.so-called “plastic” deformation. Under such circumstances, the pressureinside the capsule is clearly smaller.

In a preferred implementation of the invention, when the two films areassembled together around the outline of said blister, the sealingincludes a fraction of reduced width to constitute a weak region.

Thus, when the capsule is squeezed, opening takes place through the weakregion of the sealing, at the interface between the two films.

Advantageously, a fraction of said portion of said first filmconstituting the blister is transformed locally so as to constitute aweak region.

The particular feature of this implementation lies in the fact that thecapsule is opened through a face of said first film, and not via itsinterface with the second film. In this configuration, it is possible toeject the topical composition from the center of the capsule and notnecessarily from the peripheral seal of said capsule.

Finally, in order to weaken the film locally, it is possible to flattenthe film or to deform it, or else to melt the film locally by means of aheater or an ultrasound device.

In another preferred implementation, suction is established between aportion of the deformable first film and a recess so as to apply saidfilm portion against the inside wall of said recess so as to constitutesaid blister.

It will be understood that the fact of placing the film over a cavityconstituting a recess and of establishing suction between said film andsaid cavity tends to press the film against the inside wall of saidcavity. Naturally, this wall has orifices enabling air to be sucked out.

In another preferred implementation, said first film and said secondfilm are sealed together by means of an ultrasound device.

This implementation presents the advantage of melting only thoseportions of the film that are in contact, and of not including any heatsource that might damage the capsule or its content.

Advantageously, the encapsulation method of the invention is applied tomaking pads. For this purpose, at least a first sheet of foam is appliedand secured to the outside wall of said first film in order toconstitute the pads.

A layer of foam is applied to the capsule made in accordance with theinvention for the purpose of spreading said composition on the skin. Thefoam is secured to the capsule via the edges of the two films that aresealed together.

In order to make both faces of the pad agreeable to the touch, it ispreferable to apply a second sheet of foam and/or of textile material onthe outer wall of said second film.

In order to protect at least the face that includes the applicator foam,a protective film constituting a membrane is advantageously applied tosaid first sheet of foam.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Other features and advantages of the invention will appear on readingthe following description given by way of non-limiting indication andwith reference to the accompanying drawing, in which:

FIG. 1 is a highly diagrammatic plan view of an installation forcontinuously encapsulating and making pads; and

FIG. 2 is a diagrammatic longitudinal section view through theinstallation for continuously encapsulating and making pads.

DETAILED DESCRIPTION OF THE INVENTION

The method of making a capsule containing a topical composition isdescribed below with reference to FIGS. 1 and 2.

A first film 2 wound on a reel 4 is suitable for being unwound in thedirection of an arrow F through an installation for making capsules 6.The film 2 is moved sequentially in the direction of arrow F, with thesequences corresponding to the time required for making the capsule 6.

In a first step, while the film 2 is stationary a vacuum pump 8 isactivated so as to suck the film 2 into a cavity 10 constituted by arecess. The cavity 10 has orifices pierced through its wall for passingair so that the film 2 is pressed against said wall.

The plastics material film is relatively elastic, and under the effectof the suction, it tends to deform so as to take up the shape of therecess without any creasing appearing around the periphery of theblister 14 formed by the sucked-in portion of the film 2.

The film 2 can be made of polyethylene or of polyether, or it couldalternately be of polyurethane which has the advantage of being highlyelastic compared with other types of film.

During a second step of the method, while suction is maintained on thefilm 2, and consequently while the resulting blister 14 is held inshape, a topical composition is injected into said blister 14 by meansof a filler spout 16.

The spout 16 is constituted by a bent tube 18 pivoted at one end by arotary coupling 20 so as to be capable of being retracted betweensuccessive steps of filling said blisters 14. Upstream from the spout,there is a piston metering pump that dips into a tank storing thetopical composition. The pump is actuated when the end of the spout 16is vertically over the blister constituted by the portion of film 2.

Once the blister 14 has been filled by injecting a measured quantity ofsubstance that is substantially equal to the volume of the cavity 10,the spout 16 is pivoted away by means of the coupling 20 so as to bespaced apart from the blister.

Together with the film 2, a second film 22 superposed over the film 2 issuitable for being moved along arrow F. The width of the film 22 issubstantially equal to that of the film 2 and the film 22 is wound on areel 24. Up to the cavity 10, and thus up to the blister formed in aportion of the film, these two films are sufficiently far apart toenable the filler spout 16 to be inserted between them.

During a third step, the film 22 is applied to said portion of the film2 so as to cover and close the blister 14 containing the topicalcomposition.

This third step is performed simultaneously with a fourth step in whichthe two films 2 and 22 are sealed together by means of an ultrasounddevice 26. The device is driven vertically along arrow D and is pressedagainst the two films 2 and 22 around the periphery of the cavity 10 onthe edges of the recess. The two films 2 and 22 are pressed togetherbetween two substantially circular metal elements all around theperiphery of the blister, and they are subjected to the effect ofultrasound type vibration (i.e. at a frequency greater than 20 kilohertz(kHz)) imparted to the two films 2 and 22 by these two metal elements.The films become bonded together by local melting.

In a particular implementation, the capsule 6 has a region of weaknessin the seal between the two films 2 and 22 to enable the capsule to beopened.

To make this region, the vibrating metal elements are pressed intocontact with the periphery of the blister and the two films 2 and 22 areheated between them. In at least one fraction of their contactingportions, said metal elements are narrower than around the remainder ofthe periphery of the blister. Thus, the width of the seal in at leastsaid fraction is itself narrower than the width of the seal around theremainder of the blister, thereby constituting a weak region.

In use, the capsule is squeezed so as to break said weak region andrelease the topical composition.

In another particular implementation, the capsule presents a weak regionover a fraction of said film that constitutes the blister. For thispurpose, provision is made to transform a localized fraction of the filmby deforming it or flattening it. These operations are performed bymeans of a device that is not shown but that is situated upstream fromthe device for forming the capsule.

The two films can also be sealed together by means of so-called “highfrequency” techniques which present the advantage, like ultrasoundtechniques, of not heating the environment in which they are used. Thefilms used for encapsulating the topical composition are relativelyfragile, and a device of the hot iron type would tend to heat a largerarea of the film excessively and would also run the risk of damaging thetopical composition contained in the capsule.

Naturally the material used for making the films 2 and 22 isthermoplastic, since otherwise heat sealing would not be possible.

Once the time required for sealing has been achieved, the device 26 israised vertically along arrow R so as to release the two films 2 and 22as sealed together in this way. The capsule containing the topicalcomposition is thus hermetically closed.

The operation of the vacuum pump can then be interrupted so as torelease the capsule from the cavity 10 in which it is to be found. Whenthe capsule is released, the film 2, which presents elastic properties,retracts and exerts a certain amount of pressure on the topicalcomposition, thus tending to make it easier to release the compositionwhen the capsule is opened.

Depending on the nature of the film, this deformation is elastic to agreater or lesser extent. The greater the extent to which thedeformation is elastic, the higher the internal pressure inside thecapsule, thereby causing the topical composition to be released morequickly and more fully.

In order to release the capsule from the cavity in which it is to befound, provision is made for the strip of film 22 to make a certainangle α with the horizontal, and consequently relative to the strip offilm 2, such that when the tension in the film 22 is greater than thetension in the film 2, and when the cylinders 28 and 30 are raised to acertain extent, the capsule is released from the cavity 10.

The two films 2 and 22 can then be moved together in the direction ofarrow F so as to move the previously made capsule 6 out of the way andenable a new capsule to be made. The capsules are thus connectedtogether by the two superposed strips of film 2 and 22.

The films thus advance sequentially, and the capsules are made in such amanner that the distance between them is sufficient to enable thesubsequent operations of forming the pad to be performed.

In the embodiments shown in FIGS. 1 and 2, the installation alsoincludes peripheral equipment for making a pad.

A punch 32 is situated over the strip of capsules 34 at a distance fromthe cavity in which the blisters are formed that is a multiple of theinter-capsule spacing. This disposition enables a pad to be formedduring the time required to make a capsule.

The outside wall of the blister 14 constituted by the capsule 6 hassimultaneously applied thereto: padding foam 36; applicator foam 38; anda protective membrane 40. Like the films 2 and 22, the foams 36 and 38,and the membrane are applied as continuous strips during the continuousprocess of encapsulation and pad provision.

While the capsule is received in the bottom portion 42 of the punch, thepadding and applicator foams and the film constituting the membrane arepressed against the outside wall of the blister constituting thecapsule. Thereafter, the top portion of the punch 32 is pressed andforced against the bottom portion 42 so as to cut out the set ofelements constituting the pad in the desired shape.

The punch 32 includes a device serving, simultaneously with thecutting-out operation, to seal together the edges of the various layersso that the pad does not have an edge that might hurt the user.

What is claimed is:
 1. A method of encapsulating a topical compositionin a breakable capsule constituted by at least a first deformable filmthat is impermeable to said composition, the method comprising the stepsof: a first step comprising deforming at least a portion of said firstfilm elastically so as to constitute at least one blister; a second stepcomprising injecting said topical composition into said blister; a thirdstep comprising applying a second film that is impermeable to saidcomposition onto said first film so as to close said blister; and afourth step comprising sealing together said second film and said firstfilm around the periphery of said blister, said portion of said firstfilm being suitable for shrinking after release of said capsule so as tocause the pressure inside the capsule to be greater than atmosphericpressure; wherein, while said capsule is being made, making at least oneweak region at least in said blister, thus making the capsule suitablefor being broken by exerting pressure on said capsule.
 2. A methodaccording to claim 1, wherein said portion of the first filmconstituting said blister is subjected to deformation that is bothplastic and elastic such that said first film shrinks in part after saidcapsule has been released, whereby the pressure inside the capsule isnot less than atmospheric pressure.
 3. A method according to claim 1,wherein the seal includes a fraction of reduced width to constitute aweak region.
 4. A method according to claim 1, wherein a fraction ofsaid portion of said first film constituting the blister is transformedlocally so as to constitute a weak region.
 5. A method according toclaim 1, wherein suction is established between a portion of thedeformable first film and a recess so as to apply said film portionagainst the inside wall of said recess to as to constitute said blister.6. A method according to claim 1, wherein said first film and saidsecond film are sealed together by means of an ultrasound device.
 7. Amethod according to claim 1 for making pads, wherein at least a firstsheet of foam is pressed against and secured to the outside wall of saidfirst film to constitute the pads.
 8. A method according to claim 7,wherein a second foam sheet and/or textile material is applied againstthe outside wall of said second film.
 9. A method according to claim 7,wherein a protective film is also applied to constitute a membrane onsaid first sheet of foam.